Hydrogenating catalyst



- UNITED STATES P TEN ET-o Flc afia; maocnna'rmo CATALYST Rhea Watts,

Baton Rouge, La, assignor to Stand ard- Catalytic Companyv No Drawing.Application June 13, 1941,

Serial No. 397,871 a Claims.

' This invention relates to the preparation of catalysts and pertainsmore particularly to the preparation of catalysts for the hydrogenationof petroleum oil and other carbonaceous materials.

The present application forms a continuationin-part of my earlier'application Serial No.

204,313, filed April; 26, 1938.

It has heretofore been proposed to prepare hydrogenating catalysts bycoating or impregnating a porous carrier with an active hydro-- genatingcatalyst, such as, for example, the oxides or sulphides of the metalsofgroup VI of the periodic "system and particularly the oxides orsulphides of tungsten and molybdenum. Various types of carriers having aporous or capillary structure such as adsorptive clays, activatedcarbon, silica gel, kaolin, kieselguhr and others have been suggested.

This invention finds particular application to the preparation ofhydrogenating or dehydrogenating catalysts comprising a support such asadsorptive clay impregnated with a tungstate or molybdate salt solution.

In accordance with present practices, the catalyst is prepared byimpregnating the carrier with a dilute solution of ammoniumthiotungstateor ammonium thiomolybdate.

According to previous practices, the 'ammonium thiotungstate, forexample, was prepared by reacting tungstic oxide (W03) with ammoniumsulphide solution through which an excess of hydrogen sulphide waspassed so that all of the tungstic oxide was converted to ammoniumthiotungstate. Whenoperating in this manner,

solubility of the ammonuim thiotungstate in the ammonium sulphidesolution is relatively low, amounting to from 45 grams to '10 grams perliter calculated as tungstic oxide (W03) In view of the low solubilityof this material, it was heretofore necessary to .employ weakimpregnating solutions, and to build up the necessary concentration ofthe tungstic oxide or sulphide it-was necessary to form a thin slurry ofcatalyst solutionv and carrier which had to be dried before molding. wasnecessary to further dry the molded product in the absence of air and tosubject the product to a reducing treatment before use.

The present invention is dirctedto an improvement in the process ofpreparing a catalyst of the general nature above outlined.

.One of the principal objects of the invention is to provide an improvedprocess which is more simple in that it requires fewer procedural stepsciency than catalysts of similartype heretofore produced.

Following the molding operation, it

will be apparent from the more detailed description hereinafter.

I have found that the above and other objects may be attained byfollowing the process hereinafter described.

In accordance with the broader phase of the present invention, atungstate or molybdate solution is first prepared as hereinafterdescribed in a more highly concentrated'form so that the amount oftungsten and molybdenum present in the final catalyst can be obtained bydirectly admixing the solution and carrier to form a plastic masssuitable for molding without intermediate drying treatment. Theresulting product canbe air dried without igniting and may be chargeddirectly into the reactor.

I have foundthat the catalyst formed in this manner is not only lessexpensive to produce but cepts is not so limited.

In accordance with the more specific details of the invention, anadsorptive clay which is naturally active, such as fullers earth or anadsorptive clay which has been activated by suitable treatment, such aswith acid, for example, activated clays marketed under the trade name ofSuper Filtrol, Terrana, Tonsil, or Marcil, is first treated with adilute solution of hydrofluoric acid. This treatment is accomplished byintimateiy admixing the clay with the acid of about 8% concentrationfora period of about 20 minutes. The product is thereafter thoroughlydried by passing through a Herreschoff type furnace wherein it is heatedto a temperature of 220 F. to about 320 F.

This product, after being'granulated, forms the carrier or support forthe active catalyst.

The product so produced is then impregnated witha solution prepared asfollows: Tungsten trioxide is digested in an ammonium sulphide solution,the amount of sulphide present being insuflicient to completely convertthe trioxide into ammonium thiotungstate. As a result, the product isnot pure ammonium thiotungstate but contains some arrmionium tungstateand some intermediate partially sulphided compounds, such as (NHOzWOzSa.The solubility of the resulting product is much higher than pureammonium thiotungstate. The solution, for example, may

' contain from about to 250 grams of tungsten, determined as tungstentrioxide, per liter of solution.

. lubricant may be incorporated into the mixture to facilitateextrusion. The product so formed may be used directly as a hydrogenatingcatalyst. In some cases, it' may be desirable to subject the catalyst toa sulphidizing treatment either prior to or following the forming of themixture into pellets. Such sulphidizing treatment may comprise. forexample, heating it in a hydrogen sulphide atmosphere at a temperatureof 700 F.

for a period of about six hours. This treatment is preferablyaccomplished after the catalyst is charged to the reactor. Ammoniumthiomolybdate may be used as a substitute for the tungstate.

As a guide for carrying out the invention to obtain the best resultstherefrom, the following specific example may prove helpful.

l Ezample 3938 grams of tungsten trioxide (W01) were dissolved in' 17.5liters of ammonium sulphide solution prepared by reacting a 6.4%solution of NH: with H23 at room temperature and atmospheric pressure.To insure complete solution, the

mixture was agitated for 1 hour at 160 F. The resulting product had aspecific gravity of 1.206

at 90 F. and contained 225 grams per liter of tungsten expressed as W03.This product, as previously described, is not a solution of pureammonium thiotungstate but -contains some ammonium tungstate andintermediate oxy-sulphide compounds since pure ammonium thiotungstate issoluble only to the extent of from 40 to 70 grams per liter of solution.

4.160 liters of the solution so formed was combined with 10 kilograms ofactivated clay known under the trade name of Super Filtrol which hadpreviously been subi ected to hydrofluoric acid treatment for 20 minutesand subsequently dried at a temperature of 260 F. The mixture wasthoroughly agitated. A small amount ofhydrogen sulphide was firstevolved and the mixture became a reddish-brown in color with theevolution-of a small amount heat. As the mixing of about 1 centimeter indiameter and two centimeters in length.v 1

" To determine the hydrogenating efiiciency,'the product was placed in ahydrogenation chamber through which a mixture of 38.4 A. P. I. gravitykerosene was passed through while under a pressure of 3000 pounds persquare inch, in which the amount of hydrogen amounted to about 12,000

cubic'feet of hydrogen per barrel of oil. The hydrogenatingchamber wasmaintained at an average temperature of 698 F. The oil was passedthrough the chamber at the rate of 1130 5 barrels per day. The resultingproduct had an A. P. I. gravity of 58.4.

Another catalyst of the same composition prepared according to the wetprocess forming the conventional method of preparation when operatingto'produce the same quality of final product, namely, A. P. I. gravityof 58.4 under slightly higher temperature conditions, required anaverage feed rate 'of 1020 barrels per day. These comparative tests showthat the catalyst prepared according to the present invention under thesame temperature conditions permits a greater through-put. Conversely,when maintaining the same through-put the catalyst prepared according tothe present invention would permit lower operating temperature.

Having described the preferred embodiment of the invention and givenspecific examples thereof, it will be understood that it embraces suchother modifications and variations as come with in the spirit and scopethereof.

I claim: 1

1. A method of preparing a hydrogenating catalyst comprising a group VImetal compound of the class consisting of tungsten and molybdenum whichcomprises reacting one of the class consisting of tungstic and molybdicoxide with ammonium sulphide, the amount of sulphide hea inginsufiicient to completely convert said oxide to the correspondingammonium thlo salt whereby the reaction product contains a mixture ofthe oxygen and sulphur compounds of molybdenum or tungsten, mixing thereaction solution with an adsorbent supporting material. controlling the1 concentration of the solution and the amount of adsorbent materialused to'form a plastic mass suitable for molding without intermediatedrying, and molding the resulting product into units of uniform size.

- 2. A method of preparing a hydrogenating catalyst comprising a groupVI metal compound of the class consisting of molybdenum and tunastenwhich comprises forming a solution containing a mixture of the thio saltand normal salt of the said metal having a concentration of the metalcompound calculated as trioxide of at least 200 grams per liter, mixingwith said solution an adsorbent carrier in an amount sufiicient to forma plastic mass suitable for molding without prior drying treatment, andthereafter molding the resulting product. 7

3. In the method defined by claim 2. the further improvement whichcomprises forming with am-, monium sulphide a solution containingammonium thiotungstate and ammonium tungstate and admixing said solutionwith a carrier.

4. In the method defined by claim 2, the further improvement whichcomprises employing hydrofluoric acid treated bentonite clay as acarrier which is admixed with said solution.

5. In the method defined by claim 2, the further improvement whichcomprises forming with ammonium sulphide a solution containing ammoniumthiotungstate and ammonium tungstate and admixing said solution with abentonite clay as 70 a carrier.

RHEA WATTS.

